Drier control



A. w. LlssAuER DRIER CONTROL hFiled April 17, 1926 uy E@ i923..

ywentoz @tmf 115mm@ Patented' July 1o, 1928.

UNiTED STATES raiiii'ai" orrlcE.

ADOLPH W. LISSAUER, OF LOUISVILL, KENTUCKY, ASSIGNOR TOlLOUISVILLE DRY- ING MACHINERY CO., INC., OF LOUISVILLE, KENTUCKY, A CORPORATION OF KEN- TUCKY.

Daran CONTROL.

Application filed April i7,

My invention relates to a method for controlling the drying in rotary driers of tubular type and the arrangement ot' the controlling means to carry out the said method'.

An object of the invention is to deliver the. material from the drier at a predetermined moisture content by varying the temperature. of the heating medium through means accted by the temperature of the material being delivered from the drier and also by varying the volumeI of the air passing through the drier by means aifected by the temperature of the products of the evaporation leaving the drier.

Another object of the invention is to provide a thermostatic control for the drier of the type referred to, which is simple in construction and does not require skilled help for the operation of the drier.

-In the appended drawing, forming part of this application, the igure illustrates a diagrammatic elevation of a drier partly in section and embodying my invention.

In this type of drier-s, the work of evaporation is done by transmitted heat which obviously is at the same ten'iperature from one end of the drier to the other. However, as the condensation in the tubes, or the drop in the temperature of gases in the tubes is pro;` portionate to the work done by them at each point, the tubes transmit considerably more heat units at the wet end ot the drier than at the dry end. Only suliicient atmospheric air is allowed to enter the drier by regulation of the .damper in the vapor stack to carry ott' the steam which is evaporated by the action of the tubes. The vapors leave the drier practically saturated or normally about.95% of saturation. The air does no drying, but acts merely as a vehicle for the evaporated water. For this reason. the vapors tend to bc approximately at the temperature ot' atmospheric steam and it there is too much air passing through the drier, obviously the temperature of the vapors will drop. On the other hand, if thereis not enough air, the temperature of the vapors will rise.

If the material is discharged too dry, it tends to raise the temperature to correspond to the dry bulb temperature of the entering air, plus the unused heat in the drier, coming 1926. Serial No. 102,679.

from the tubes. If,on the other hand, the material is discharged too wet, it will be at the temperature of the wet bulb ofthe air, a difference of often 209. A Referring to the drawing, 1 i-s a rotary drier provided with tubes 2 through which the heating medium of the drier is circulated. Some of these tubes in the figure are broken away at the discharge end to better illustrate the discharge openings 5 of the drier. The tubes are retained in heads 3 and 12 of the drier. The head 3 located at the discharge end has a -suitable manifold tovdeliver steam or any other heating medium from a pipe 4 to thetubes 2Q The pipo 4 is provided with a diaphragm controlled valve 6. The diaphragm 7 of the valve is connected by aI conduit 8 to a thermostat'S). This thermostat is so located that tionary casing 15 which establishes the communication between the stack and the drier. A damper 16 is provided in the stack 14 and the same is operated through a series ot levers 17 by a diaphragm 18. This diaphragm is connected hy a conduit 19 to a thermostat 20 located in the passage leading from the opening 13 of the drier to the stack 14. The two thermostat-s 9 and 20 are both connected to a conduit 21 through which colnpressed air is supplied. Each of the thermostats has a graduated control and is direct acting.

As will be noted, the material to be dried passes in a direction opposite to the air which is tocarry ott the products of evaporation. The thermostat 9 located at the discharge end of the drier is necessarily affected by the temperature of the material being discharged therethrough. In consequence, with the rise of the temperature thereat, a reduction in the temperature of the heating medium admitted will necessarily occur. The reverse will be true when there is a drop ing through the 'products of evaporation.

reverse is the case when the temperature of.

the vapors passing into the stack drops.

I claim:

1. In a method of drying material inay drier steps which consist in Ycontrolling the temperature of the heating medium of the drier by the temperature of the material 'being discharged from the drier, and controlling drier by the temperature or the products of evaporation leaving the drier.

2. In a method of drying material in a drier steps which consist in supplying a heating mediumto the drier, moving the material to be dried through the drier, passing atmospheric air through the drier in a direction op osite to that of the material, controlling tlhe temperature of the heatin medium by the temperature of the materia' being discharged from the drier, andcontrollin the volume of the air passing throug the drier by the temperature of the products of evaporation leaving the drier.

3. In a method of drying materialina drier steps which consist 1n supplying a heating medium to the drier, feeding the material to be dried through the drier, passing atmospheric air through the drier to .carry oi the products of evaporation,'con trolling the temperature of the heating medium by the temperature of the material being` discharged b the drier, and controlling the volume of t e atmospheric airpassing through the drier by the temperature of the 4. In combination with .a rotar drier I having material charging and disc arging the volume of the atmospheric airl pass-1 l infiuenced by apertures and open to the atmosphere, of means for supplying a heating medium to the drier, a diaphragm valve controlling the flow of the heating medium, a thermostat 1ocated at the discharge aperture controlling the diaphragm valve, a stack for carrying 'of -'thepoducts of evaporation,.a in the `stack1;for.controll in the llow 'of atmospheric airwith the p ro ucts of evaporation, a...diaphragmfor operating the damper, and a thermosttlgforoperatiug the dia hragm and disposed to be"'iniluenced by t e temrature' of thev 'products of evaporation caving the drier. p l 5. In a rotary tubular drier a dia hragm l valve for controlling the ow ofv a eating 00 medium to the tubes, a thermostat for oontrolling the diaphragmvalve dis osed to be ty e tem erature othe-material being discharge from the .drier'fa damper for controlling the flow of rbducts 045l i of evaporation from the drier, an a thermostat for operating the damper disposed to be influenced by the temperature of the products of evaporation leaving the drier,

6. In a method of drying material ina.70

drier, steps which consist in circulating att mospheric air through the drier to carry off the products of evaporation `and varying the v volume of the air circulatedl in the drier by the temperature ofthe productsI of evaporatoncarried o (by the air.A Y

7.In a meth ofldrying material vin a drier, steps which consist' in controlling-the temperature of the heating medium o the drier by the tem erature of the material being' discharged groin the drier, circulatin "air through the drier to carry oif the p ucts ofl evaporation and varying the volume of the air [circulated through the drier through a control operated by the temperature of the products of-evaporation carried off by the'air from the drier.

ADOLPH W. LISSAUER. 

